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Emissions of ozone-forming gases (ground-level ozone precursors) were reduced by 33% across the EEA member countries between 1990 and 2002, mainly as a result of the introduction of catalysts in new cars.

Key messages

Emissions of ozone-forming gases (ground-level ozone precursors) were reduced by 33% across the EEA member countries between 1990 and 2002, mainly as a result of the introduction of catalysts in new cars.

What progress is being made in reducing emissions of ozone precursors across Europe?

Total emissions of ozone precursors were reduced by 33 % across the EEA member countries between 1990 and 2002. For the EU-15 countries, emissions were reduced by 35 %.

Emission reductions in the EU-15 since 1990 are due mainly to the further introduction of catalytic converters for cars and increased penetration of diesel, but also as a result of the implementation of the solvents directive in industrial processes. Emissions from the energy and transport sectors have both been significantly reduced, and contributed 10 % and 65 % respectively of the total reduction in weighted ozone precursor emissions. Emission reductions of the ozone precursors covered by the national emission ceilings directive (non-methane volatile organic compounds, NMVOCs, and nitrogen oxides, NOx) have resulted in the EU-15 being on track to reaching the overall target for reducing these emissions in 2010.

Emissions of non-methane volatile organic compounds (38 % of total weighted emissions) and nitrogen oxides (48 % of total weighted emissions) contributed the most to the formation of tropospheric ozone in 2002. Carbon monoxide and methane contributed 13 % and 1 % respectively. The emissions of NOx and NMVOC were reduced significantly between 1990 and 2002, contributing 37 % and 44 % respectively of the total reduction in precursor emissions.

In the EU-10 (1), total ozone precursor emissions were reduced by 42 % between 1990 and 2002. Emissions of non-methane volatile organic compounds (32 % of the total) and nitrogen oxides (51 % of the total) were the most significant pollutants contributing to the formation of tropospheric ozone in EU-10 countries in 2002.

(1) Data from Malta not available.

How do different sectors and processes contribute to emissions of ozone precursors?

In both the EU-15 and EU-10, transport is the dominant source of ozone precursors. In 2002, transport contributed to 48% of total EU-15 emissions, with emissions from this sector contributing 65% of the total reduction of ozone precursor emissions between 1990 and 2002. Other important EU-15 emission sources in 2002 included commercial and domestic combustion and use of solvents in paint, glue and printing. After the transport sector, the sector responsible for the second largest absolute reduction was the energy industries sector, contributing 10% of the total reduction of ozone precursor emissions. Emission reductions that have occurred within the EU-15 region since 1990 are mainly due to the further introduction of catalytic converters for cars and increased penetration of diesel, but also as a result of the implementation of the Solvents Directive in industrial processes.

In the EU-10, transport is again the dominant source of ozone precursors and contributed 40% of total TOFP-weighted emissions in 2002. Other significant emission sources in the EU-10 include commercial and domestic combustion processes (13% of total emissions), other non-energy (8%) and energy industries (13%). As observed across the EU-15, the emission reductions observed are mainly due to further introduction of catalytic converters for cars and increased penetration of diesel, but also through the implementation of the Solvents Directive in industrial processes and reduction of fuel consumption. Emissions in the industry (processes), energy industry and transport sectors have all been significantly reduced, and contributed to 14%, 25% and 26% of total reduction of ozone precursor emissions, respectively.

The indicator also provides information on emissions by sectors: Energy industries; road and other transport; industry (processes and energy); other (energy); fugitive emissions; waste; agriculture and other (non energy).

Units

ktonnes (NMVOC-equivalent)

Rationale

Justification for indicator selection

Emissions of non-methane volatile organic compounds (NMVOCs), nitrogen oxides, carbon monoxide and methane contribute to the formation of ground-level (tropospheric) ozone. Their relative contributions can be assessed on the basis of their tropospheric ozone-forming potential (TOFP) (de Leeuw 2002).

Ozone is a powerful oxidant and tropospheric ozone can have adverse effects on human health and ecosystems. It is a problem mainly during the summer months. High concentrations of ground-level ozone adversely affects the human respiratory system and there is evidence that long-term exposure accelerates the decline in lung function with age and may impair the development of lung function. Some people are more vulnerable to high concentrations than others, with the worst effects generally being seen in children, asthmatics and the elderly. High concentrations in the environment are harmful to crops and forests, decreasing yields, causing leaf damage and reducing disease resistance.

Scientific references

No rationale references
available

Policy context and targets

Context description

Emission ceiling targets for NOx and NMVOCs are specified in both the EU National Emission Ceilings Directive (NECD) and the Gothenburg protocol under the United Nations Convention on Long-Range Transboundary Air Pollution (LRTAP Convention) (UNECE 1999). Emission reduction targets for the new EU-12 Member States have been specified in a consolidated version of the NECD for the EU-25 [1] which was adopted by the European Community after the accession of the EU-10 Member States. In addition, the consolidated NECD also includes emission ceilings for Bulgaria and Romania whose targets have been defined in their respective Accession treaties [2].

There are no specific EU emission targets set for either carbon monoxide (CO) or methane (CH4). However, there are several Directives and Protocols that affect the emissions of CO and CH4. For example, carbon monoxide is covered by the second daughter Directive under the Air Quality Directive. This gives a limit of 10 ug m-3 for ambient air quality to be met by 2005. Methane is included in the basket of six greenhouse gases under the Kyoto protocol (see CSI 10: Greenhouse gas emissions and removals).

Targets

Emissions of NOx and NMVOCs are covered by the EU National Emission Ceilings Directive (NECD) (2001/81/EC) and the Gothenburg Protocol under the United Nations Convention on Long-Range Transboundary Air Pollution (LRTAP Convention) (UNECE 1999). The NECD generally involves slightly stricter emission reduction targets than the Gothenburg Protocol for EU-15 countries for the period 1990-2010.

Directive 2001/81/EC, on nation al emissions ceilings (NECD) for certain atmospheric pollutants. Emission reduction targets for the new EU10 Member States have been specified in the Treaty of Accession to the European Union 2003 [The Treaty of Accession 2003 of the Czech Republic, Estonia, Cyprus, Latvia, Lithuania, Hungary, Malta, Poland, Slovenia and Slovakia. AA2003/ACT/Annex II/en 2072] in order that they can comply with the NECD.

Methodology

Methodology for indicator calculation

The dataset compiled by EEA/ETC-ACC for this indicator is based on national total and sectoral emissions of CO, NMVOC and NOx (expressed as NO2) officially reported to UNECE/EMEP Convention on Long-Range Transboundary Atmospheric Pollution (LRTAP Convention) and GHG Monitoring Mechanism.

Emissions data reported to the LRTAP Convention can be submitted in NFR format. A detailed discription of the difference reporting formats can be found in the EMEP/CORINAIR Emission Inventory Guidebook - 2006 (1).

Base data is available from http://webdab.emep.int/ and from the EEA dataservice. Emission data for methane is obtained from the EEA Greenhouse Gas Inventory database. Base data, reported in NFR are converted into EEA sector codes to obtain a common reporting format across all countries and pollutants:

-Energy industry: Emissions from public heat and electricity generation

-Other (energy-related) covers energy use principally in the services and household sectors

-Other (Non Energy): Emissions from solvent and other product use.

The current LRTAP template Version 2004-1 includes 103 categories.

The following table shows the conversion of NFR sector codes into EEA sector codes:

EEA Code

EEA classification

Non-GHGs (NFR)

0

National totals

National Total

1

Energy industries

1A1

3

Industry (Energy)

1A2

2

Fugitive emissions

1B

7

Road transport

1A3b

8

Other transport (non-road mobile machinery)

1A3 (excl 1A3b) + sectors mapped to 8 in table below

9

Industry (Processes)

2

4

Agriculture

4 + 5B

5

Waste

6

6

Other (Energy)

1A4a, 1A4b, 1A4b(i), 1A4c(i), 1A5a

10

Other (non-energy)

3 + 7

14

Unallocated

Difference between NT and sum of sectors (1-12)

12

Energy Industries (Power Production 1A1a)

1A1a

Where reported data from countries is incomplete, simple gap-filling techniques are used in order to obtain a consistent time-series (see section on gap-filling).

To obtain emission values for the ozone precursors, the gap-filled emission values are multiplied by tropospheric ozone formation potential factors, de Leeuw (2002). The factors are NOx 1.22, NMVOCs: 1, CO: 0.11 and CH4: 0.014. Results are expressed in NMVOC equivalents (ktonnes). For the main indicator trend graph, emissions are shown indexed to 1990 values (1990 emission =100). The sectoral shares are the share of the specific sector relative to the sum of all sectors for a given year. The 'unallocated' sector corresponds to the difference between the reported national total and the sum of the reported sectors for a given pollutant/country/year combination. This can be either negative or positive. Inclusion of this additional sector means that the officially-reported national totals do not require adjustment to ensure they are consistent with the sum of the individual sectors reported by countries.

Methodology for gap filling

To allow trend analysis, where countries have not reported data for one or more years, data have been interpolatedto derive the emission for the missing year or years.If the reported data is missing either at the beginning or at the end of the period, the emission value is assumed to equal the first (or last) reported emission value.The use of gap-filling may lead to artificial trends, but it is considered unavoidable if a comprehensive and comparable set of emissions data for European countries is required for policy analysis purposes. A list of the gap-filled dataset, plus a spreadsheet containing a record of the gap-filled data will be made available from EEA's dataservice: http://dataservice.eea.europa.eu/dataservice/metadetails.asp?id=818

Uncertainties

Methodology uncertainty

The use of ozone formation potential factors leads to some uncertainty. The factors are assumed to be representative for Europe as a whole; on the local scale uncertainties are larger and other factors are more relevant. An extensive discussion on the uncertainties in these factors is available in de Leeuw (2002).

Data sets uncertainty

EEA uses data officially submitted by EU Member States and other EEA member countries which follow common guidelines on the calculation and reporting of emissions (EMEP/EEA 2006) for the air pollutants NOx, NMVOC and CO, and IPCC (2006) for the greenhouse gas CH4.

NOx emission estimates in Europe are thought to have an uncertainty of about +/-30%, as the NOx emitted comes both from the fuel burnt and the combustion air and so cannot be estimated accurately from fuel nitrogen alone.EMEP has compared modelled and measured concentrations throughout Europe (EMEP 1998).From these studies differences for individual monitoring stations of up to a factor of two have been found.This is consistent with an inventory of national annual emissions having an uncertainty of +/-30% (there are also uncertainties in the measurements and especially the modelling). Uncertainties in emissions of CO are likely to have a similar magnitude of uncertainty as for NOx.NMVOC emissions data have been verified by EMEP and others by means of comparison between modelled and measured concentration throughout Europe. From these studies total uncertainty ranges have been estimated to about +/-50%. Some main source categories are less uncertain.

CH4 estimates are reasonably reliable as they are based on a few well-known emission sources. The IPCC believes that the uncertainty in CH4 emission estimates from all sources, in Europe, is likely to be about +/-20 %. CH4 emissions from some sources, such as rice fields, are much larger (possibly an order of magnitude), but are a minor emission source in Europe. In 2004, EU Member States reported uncertainties in their estimates of CH4 emissions from enteric fermentation as ranging between 0.5 % (UK) and 2.8 % (Ireland) of the total national GHG emissions (EEA 2004).

Incompletereporting and resulting intra- and extrapolation may obscure some trends.

Rationale uncertainty

This indicator on emissions of ozone precursors is produced annually by EEA and is used regularly in its State of the Environment reporting. The uncertainties related to methodology and data sets are therefore of importance. Any uncertainties involved in the calculation and in the data sets need to be accurately communicated in the assessment, to prevent erroneous messages influencing policy actions or processes.